The reader should know that unlike HIV which is transmitted via sexual contact, blood transfusions and intravenous drug use, both gonorrhea and syphilis (maybe chlmaydia, though I'm ignorant of that one) are passed primarily via sexual contact (congenital syphilis notwithstanding, as that is a rare form). They are both bacterial infections, and though there are resource costs with treatment (ie, the cost of a shot of whatever antibiotic is recommended), if caught soon enough there are no real longrun consequences of having been infected. If syphilis is not caught, it'll advance to a stage that ultimately enters the person's greater vessels and can cause serious problems, even death. But because syphilis is relatively symptomatic - there's some pain associated with it, particularly while urinating, and syphilis lesions form near the area of infection (usually genitalia, but also the vagina and anus for women and infected gay men respectively, which make detection slightly less likely since the lesions are not painful) - it's more likely to be discovered before it reaches that point. Gonorrhea, if not treated, also has very severe problems in the longrun, but usually it too is treated. What I find interesting about these two STDs, though, is that they function well as a barometer for larger sexual trends. Not perfectly, mind you, as there's network effects associated with STD transmission. That is, individuals bringing the bug into a given segregated community can cause an outbreak, even though it's only the behavior of one person that was distinctively different. There was an outbreak of some STD, I forget which, at a retirement home a few years ago that had been caused by a new resident moving in. That sexual network was largely self-contained, but once the bug got into the community, it broke out because there was a lot of partner-sharing ("dating"). The article pointed to Viagra, the menopausal state of the women (therefore no pregnancy risks), their age making them fairly ignorant about safe sex practices in general, as the three main causes. But it was mainly the new resident that set the thing into motion.
So, keeping that in mind, I am still of the opinion that these rises in syphilis and gonorrhea are because of some kind of increase in risky sexual behavior at the population level. If you look at syphilis rates, for instance, you'll find that since 1998, White and Hispanic male syphilis rates have increased 500% and 200% (respectively), whereas female syphilis rates for each demographic have not changed at all. The increase is all driven by about 20 states or so - all of which have high gay male populations (CA, NY, IL, FL, GA, TX, WA, PA, NJ, etc.). Most of the growth in those states is thousands of percentage points increases - White male syphilis rates (15-45 year olds), for instance, in California increased 1,730% from 1998 to 2004 (I only have data on this to 2004). Some states have even more, but most have around that magnitude. So what's going on? Based on the data I have, it's most likely increases in syphilis among gay men - that is supported by the fact that female rates are not changing, and if it was heterosexual male increases, you'd expect to see it show up among females since an infected male will infact a non-infected female partner. But you don't see that - this is all contained by the boundaries of the homosexual male network by all appearances. Why? My hypothesis, which is not novel, is that it's the life-saving medical technology of the AIDS cocktail that is causing this increase. The AIDS cocktail, also called 'highly active anti-retroviral treatment' (HAART), particularly the 1995 FDA approval of the first protease inhibitor, have significantly increased the likelihood of surviving with HIV. The upper bound on time infected is not yet known - it's at least 20 years, depending on when you identified the infection and your ability to consistently stay ahead of the rapidly evolving HIV virus in the host's body. It's probably indefinite, though. Magic Johnson is still only HIV-positive, for instance. This has three effects.
1. It makes the sexual networks more efficient from teh perspective of an STD, assuming that HIV-positive individuals have higher numbers of sexual partners than the average of the network. Now bugs can move throughout the network faster, in other words.
2. It increases the survival of HIV-positive patients, who are now healthier and increase their partnerships (this has been shown in other studies). Syphilis is, like HIV, highly concentrated among gay males (though not exclusively), and has a high co-infection rate with HIV-positive people. Insofar as the HIV-positive population has grown, you'd expect independently this to increase syphilis rates, if the men are becoming healthier.
3. Finally, the expected costs of contracting HIV are lower as a result of HAART. You can live longer now with HIV. As such, the expected costs of having sex with other men is lower. So theoretically, this constitutes a price reduction in the price of risky sex, causing both a substitution towards mroe risky sex (fewer condoms, more partners) and an increase in net sex altogether (the so-called "income effect" for those who remember their indifference curves from intermediate micro).
The increase in gonorrhea is stranger, though. You can see that gonorrhea has been flat since 1998, even while syphilis rates have been rising. As gonorrhea is more of a Black STD, I'm interested in studying this more closely.
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